Process for water and flame proofing textiles



lflh l ti United! assignor to John P. Wetherill, Charles M. Trammell, and Alexander M. L. de Luxembourg, trustees No Drawing. Application November 30, 1955, S erialNo. 550,172

Claims. (Cl. 117-93) This invention relates to improved water-andflame proof fibrous materials and more particularly to' amethod for the production of waterproof and flame-proof textile materials.

Heretofore various solutions of metallic salts have been used for flame-proofing and water-proofing fibrous materials. Lead acetate, calcium acetate and ammonium chloride solution and mixtures thereof have been usedfor many years. A later development having the same genera-l objects included theuse of stannate as apreliminary impregnating material, followed by the use of a solution of a soluble salt; that would react therewith, that would produce a precipitate. A still later development also required a double impregnation, first with a solutionof aluminum, nickel, chromium, lead etc. and then treating with a solution of amineniumhydroxi'de toprecipitate the hydroxide of the metal. A development abroad, approximately fift'y years ago, describes the treatment of a textile material with a solution of metallic salts and then with a second solution capable of acting on this metallic salt to produce a precipitate.

It has long been recognized that all of these processes depend on the production of an insoluble compound ad-- jac'ent to the fibers composing the substance so treated, and render the same harsh and non-yielding to the touch and have universally proven unsatisfactory.

It is an object of the present invention to treat a fibrous material with a solution of a soluble substance so as to incorporate this substance within the fiber cells andthen treat in such a manner as to cause this substance to render the cloth permanently water-proof and flameproof. The prior treatments are well known to cause deterioration of cellulosic materials, due to light radiation in the presence of stannic oxide and some treatments have incorporated certain pigments to prevent this action.

it is another object of this invention toproduce waterrepellent fibrous materials, such as water-repellent. cotton, linen, silk, wool, rayon and similar textiles as well as felt, canvas, paper and the like.

Another object is the production of water-repellent fibrous materials wherein the pores of the materials are not obstructed by undesired deposits.

A further object is the production of fiame-and-water repellent textiles and similar fibrous materials having the fibers completely water-repellent throughout the body of the fabric.

Yet another object is the provision of a rapid and economical treatment whereby textiles and similar fibrous materials are rendered both water-proof or water-repellent and fire-proof or fire-retardant.

Other and further objects will be apparent or will appear as the ensuing description proceeds.

The foregoing objects are accomplished in accordance with this invention wherein a fibrous material is treated with an aqueous mixture of aluminum sulfate, lead acetate and hexamethylenetetramine, thereafter exposing the thus-treated material to black rays of the infra-red radia- L FQFNGF 2,780,566 btented Feb. 5, 1957 tion. Additionally, this invention: contemplates the further treatment of the textile or other fibrous material with a soluble tinsalt while again exposing. the treated material to infra-red radiation, whereby a material is produced which is both water repe'llent and fire-resistant or fire-proof.

In the practice of my invention a hot solution of lead acetate is admixed with a hot solution of aluminum sulfate; A precipitate is formed as it is well known that lead sulfate is not extensively soluble inhot water, but it is more soluble in hot water than: in cold Water, and more soluble in aluminum acetate solutions than it is in water. Thereafter, a small amount of hexamethylenetetramine is added which immediately dissolves that part of the precipitate remaining. in suspension. The then clear solution is separated from that part of the precipitate that had previously settled out. A suitable fibrous substance is then treated with the solution and thereafter exposed-to the black rays of the. infra-red beam. There results by this treatment a fibrous material of superior properties in which pores of each fibre are impregnated with-'the' treating agents, which material can be repeatedly laundered or'dry-cleaned'without losing its water-repellent and flame retardant characteristics. The

textile thenbe'comes fiam'e proof for about four years and is not. thereafter'damaged by visible light rays as are the products of the prior art.

lncarrying out my invention, I have found the procedure of the following example to give very satisfactory results. In the example", parts and proportions are by weight unless otherwise designated.

. Example I] 325 grams of lead acetate are dissolved in one. half of a gallon of boiling water, preferably distilled Water, and

admixed with a solution of grams of aluminum sul fate in one-half gallon of'hot water, preferably'distilled' water. The resulting turbid solution or mixture has'the color and consistency of milk. Thereafter, a five grain tablet of hexamethylenetetramine, sold under the trade.

name Urotropin, is dissolved in the previously prepared turbid mixture. The mixture then becomes clear, and a small amount of residue which. settles on the bottom isv discarded. The solution is filtered through a cloth and into this clear solution, is immersed the textile material'- to be treated, for example a khaki uniformv material of cotton, and the immersed material is exposed to the radiation from a suitable infra-red lamp, preferably for a time about fifteen to thirty minutes. The preparation of the solution and textile material is preferably carrie'ci' out in adark room, with of course, the exception of the infra-red treatment. The treatedmaterial is next withdrawn from the treatment solution,-and again exposed to infra-red radiation whereupon. it becomes water-repellent.

In treating, the cloth as set forth above, consideration must be given to the weight of the cloth. A thin twill, such as that used in army uniforms may be treated in twelve to fifteen minutes, while a heavy wool cloth, such as that used in army overcoats will take from fifteen to twenty-five minutes, twenty minutes being the preferred time.

Although the example describes the treatment of a cotton khaki uniform material, the invention is not limited to the specific material there described, but I can as well water-proof and flame-proof such absorbent fibrous materials as wool, silk, rayon (including regenerated cellulose and acetate rayon) and such synthetic polymeric fibrous materials as are absorbent.

Although I have secured superior results by the employment of a solution of lead acetate admixed with aluminum sulfate, and believe that this particular reaction mixture possesses peculiar virtues, solutions of aluminum acetate and hexamethylenetetramine otherwise prepared can also be employed.

I have found that the small amount of hexamethylenetetramine employed appears to act as a unique catalytic agent in aiding the fixation of the chemicals on the fibrous materials under the influence of the black rays of the infra-red radiation. Other amino compounds such as urea and ethylamine, may be used in catalytic quantities with somewhat inferior results.

I have found that in general the preparation of the treatment mixture should be carried out in the dark or with red bulb lights, that is to say while excluding sunlight and artificial light, and that the exclusion of light during the initial preparation and treatment facilitates the production of a superior product.

Although any suitable source of infra-red radiation may be employed I have found that most excellent results are secured when the radiation is beamed upon the textile fibers or other materials undergoing treatment. By the expression in infra-red radiation is meant the range of radiation lighting beyond the visible spectrum on the red side, which has a Wave length shorter than the socalled short radio waves; The wave lengths Will depend upon the temperature of the filament in the infra-red lamps and it is well recognized that radiation of various wave lengths produce different chemical reactions. Some effect is obtained by any infra-red lamp, but it is preferred that the infra-red lamp having a filament temperature in the neighborhood of 1400 C. be used. This will produce radiation of about one micron in wave length, and will produce results better than that obtainable by a 7- micron radiation. Much higher frequency may be used than the one micron radiation and has been found to work satisfactorily to produce the necessary chemical reaction between the various constituents of the treating solution.

While I have found that three parts of lead acetate is a preferred proportion to employ with five parts by weight of aluminum sulfate, these proportions can be varied considerably to secure some improvement in water-repellent properties. For example, the proportion of lead acetate can be varied between about one and five parts by weight to between about three and seven parts by weight of aluminum sulfate. The treatment mixture can be made more or less dilute than specified in the example, and I have found that a total treatment solution of between about one-half and five gallons can be employed using the stated proportions of lead acetate and aluminum sulfate. The quantity of hexamethylenetetramine employed as a catalyst is in general very small, although a large excess does not appear to do substantial harm to the resultant treated fabric. The stated proportion of five grains of catalyst to one gallon of prepared solution has beefi found very satisfactory, and as little as one grain produces some effect.

By the practice of my invention, new water and flameproof articles are prepared wherein the entire fiber is rendered water-and-flame proof and not merely the outer surface thereof.

My invention is eminently suitable for Water-and-flame proofing of uniforms, clothing, equipment, awnings, theater scenery and curtains, tents, upholstery, parachutes, balloon cloth, drapes, rugs, mattresses and many other fibrous materials too numerous to mention.

From the foregoing, it is apparent that I have provided new water-repellent fibrous materials and a simple, economical process for their preparation. The materials treated by my invention are stable to repeated laundering and dry cleaning, and my process largely involves only the consumption of cheap and readily obtainable chemicals.

One of the advantages of the fibrous material waterand-fiame-proofed, in accordance with this invention, is that there are no apparent changes in color, softness, and flexibility of the resulting fibrous materials.

Since many apparently differing embodiments of the invention will occur to one skilled in the art, various changes can be made in the details illustrated and described without departing from the spirit and scope of the invention.

What is claimed is:

1. A process for the production of a Water repellent and flame-retardant fibrous material, which comprises treating a fibrous material with a hot aqueous solution of a mixture of aluminum sulfate, lead acetate and hexamethylenetetramine, and exposing the thus treated material to infra-rec radiation during the treatment, and subsequently thereto with infra-red radiation.

2. A process as claimed in claim 1, wherein the infra red radiation has a wave length of about 1 micron, the material being exposed for approximately 12 to minutes.

3. A process for the production of a water repellent and flame retardant fibrous material, which comprises treating a fibrous material with a heated aqueous solution resulting from mixing solutions of aluminum sulphate, lead acetate and hexamethylene tetramine, and separating the precipitate, and exposing during treating the fibrous material with the black rays of the infra-red radiation.

4. A process as claimed in claim 3 wherein the infrared radiation has a wave length of about 1 micron.

5. A water proof and flame retardant soft fibrous material having Within the pores of the fiber a reaction product of aluminum sulphate, lead acetate and hexamethylene tetramine.

References Cited in the file of this patent UNITED STATES PATENTS 2,343,186 Hopkinson Feb. 29, 1944 2,520,103 Loukomsky Aug. 22, 1950 2,542,064 Tilden Feb. 20, 1951 

3. A PROCESS FOR THE PRODUCTION OF A WATER REPELLENT AND FLAME RETARDENT FIBROUS MATERIAL, WHICH COMPRISES TREATING A FIBROUS MATERIAL WITH A HEATED AQUEOUS SOLUTION RESULTING FROM MIXING SOLUTIONS OF ALUMINUM SULPHATE, LEAD ACETATE AND HEXAMETHYLENE TETRAMINE, AND SEPARATING THE PRECIPITATE, AND EXPOSING DURING TREATING THE FIBROUS MATERIAL WITH THE BLACK RAYS OF THE INFRA-RED RADIATION. 